1. Field of the Invention
The present invention relates to a technique for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator.
2. Description of Related Art
Identification Friend or Foe (IFF) monopulse interrogators are typically used to determine an azimuth bearing of a target such as an aircraft. The target azimuth bearing is determined by processing magnitudes of monopulse ratio measured by a horizontally rotated beam of two-channel monopulse antenna.
In the presence of multipath signals arising from target images on nearby reflectors, the IFF monopulse ratio becomes complex having a real part and an imaginary part. The real part of the complex monopulse ratio has been used to obtain an estimate for the target azimuth, hereinafter it is called the traditional target azimuth.
The standard deviation of traditional target azimuth has been used as a flag to indicate the presence of multipath signals. Processing either the magnitude or the real part of the complex monopulse ratio yields inaccurate values for the target azimuth which can lead to target trajectories experiencing a bias and wandering azimuth.